Gene expression as a biological dosimeter: effects of different neutron energies

In the radiation biodosimetry field, transcriptomic studies seek to determine whether the expression of a small set of genes can be used to estimate the radiation dose that a person was exposed to. Most such studies consider only photon exposure, but in the detonation of an improvised nuclear device, neutrons would likely comprise a significant proportion of the dose. In this study, we compare the effects on gene expression in human blood between two neutron-producing radiation sources: a source designed to mimic the neutron energy spectrum of a nuclear weapon (CINF; the Columbia IND Neutron Facility at the Radiological Research Accelerator Facility) and a source from a nuclear reactor (RINSC; the Rhode Island Nuclear Science Center). The radiation sources have very different neutron energy spectra: mainly fast neutrons (CINF) versus thermal neutrons (RINSC). We have compared differential gene expression at 24 h after exposure to 0, 0.5, 1, 2, and 4 Gy total doses delivered to human blood samples from the same donors in parallel at the two sites. Our analysis suggests that there is a core response to radiation that is conserved at both sites, with larger magnitude and additional components in the CINF response. These results suggest that neutron energy does affect gene expression, and that this must be accounted for in the development of biodosimetry approaches.